Ketamine-induced neurotoxicity in neurodevelopment: A synopsis of main pathways based on recent in vivo experimental findings.

Ketamine, a phencyclidine derivative and N-methyl-D-aspartate (NMDA) receptor antagonist, is widely used as an anesthetic, analgesic, and sedative agent in daily pediatric practice. Experimental studies have suggested that early prenatal or postnatal exposure to ketamine can induce neuroapoptosis, and establish neurobehavioral deficits that are evident in adulthood. However, most of the currently available clinical evidence is derived from retrospective and observational clinical studies. We, herein, attempt a brief review of the cellular and molecular mechanisms suggested to mediate ketamine-induced developmental neurotoxicity, utilizing a selected number of recent in vivo experimental evidence.

The combination of calcium ionophore A23187 and GM-CSF can safely salvage aged human unfertilized oocytes after ICSI.

PURPOSE: Artificial oocyte activation using calcium ionophores and enhancement of embryonic developmental potential by the granulocyte-macrophage colony-stimulating factor (GM-CSF) have already been reported. In this study, we evaluated the synergistic effect of these two methods on aged human unfertilized oocytes after intracytoplasmic sperm injection (ICSI). Then, we cultured the resulting embryos to the blastocyst stage and screened them for chromosomal abnormalities, to assess the safety of this protocol. METHODS: Aged human oocytes deemed unfertilized after ICSI were activated, either by briefly applying the calcium ionophore A23187 alone (group A) or by briefly applying the ionophore and then supplementing the culture medium with recombinant human GM-CSF (rhGM-CSF) (group B). Next, the development was monitored in a time-lapse incubator system, and ploidy was analyzed by array comparative genomic hybridization (aCGH), after whole embryo biopsy and whole genome amplification. Differences between oocytes and resulting embryos in both groups were evaluated statistically. RESULTS: Oocytes unfertilized after ICSI can be activated with the calcium ionophore A23187 to show two pronuclei and two polar bodies. Addition of rhGM-CSF in the culture medium of A23187-activated oocytes enhances their cleaving and blastulation potential and results in more euploid blastocysts compared to the culture medium alone. CONCLUSIONS: This study shows that activating post-ICSI aged human unfertilized oocytes with a combination of a calcium ionophore and a cytokine can produce good-morphology euploid blastocysts.

L-cysteine's effect on modulated rat brain enzymes with forced swimming.

BACKGROUND: Forced exercise is associated with oxidative stress, and L-cysteine (L-cys) administration reduces free-radical production. AIM: To investigate whether L-cys (5 mg/kg) intraperitoneal administration can ameliorate modulated total antioxidant status (TAS), protein concentration, and the activities of acetylcholinesterase (AChE), (Na+,K+)-ATPase, and Mg2+-ATPase in rat brain after 2 and 3 hr of forced swimming. METHODS: TAS, protein, and enzyme activities were measured spectrophotometrically before and after 2 and 3 hr of exercise without or with L-cys administration. RESULTS: TAS concentration (55.6 +/- 1.5 vs. 42.1 +/- 1.0 vs. 37.4 +/- 1.2 micromol/L, p < .001), protein concentration (5.68 +/- 0.36 vs. 5.40 +/- 0.18 vs. 4.01 +/- 0.16 mg/ml, p < .01), and AChE activity (0.89 +/- 0.05 vs. 0.61 +/- 0.04 vs. 0.48 +/- 0.03 DeltaOD/min x mg protein, p < .001) were significantly reduced, whereas Na+,K+-ATPase (6.00 +/- 0.36 vs. 10.44 +/- 1.04 vs. 11.90 +/- 1.21 micromol phosphorus inorganic/hr x mg protein, p < .001) and Mg2+-ATPase activity (7.20 +/- 0.65 vs. 10.88 +/- 1.08 vs. 11.55 +/- 1.22 mmol phosphorus inorganic/hr x mg protein, p < .001) were statistically significantly increased after 2 and 3 hr of forced exercise. Post-L-cys administration, AChE activity was decreased (0.90 +/- 0.04 vs. 0.47 +/- 0.02 DeltaOD/min x mg protein, p < .001) and remained unaltered (0.64 +/- 0.04 vs. 0.67 +/- 0.04 DeltaOD/min x mg protein, p > .05) 2 and 3 hr postexercise (0.47 +/- 0.02 vs. 0.54 +/- 0.02 DeltaOD/min x mg protein, p > .05). Na+,K+-ATPase was decreased and remained unchanged (1.85 +/- 0.17 vs. 1.77 +/- 0.19 mumol phosphorus inorganic/hr x mg protein, p > .05) 2 and 3 hr postswimming (1.91 +/- 0.19 vs. 2.06 +/- 0.17 mumol phosphorus inorganic/hr x mg protein, p > .05). Mg2+-ATPase activity was similar with L-cys supplementation pre- vs. postswimming. CONCLUSIONS: L-cys administration might ameliorate modulated rat brain enzyme activities induced by free-radical production during forced swimming.

l-Cysteine and glutathione restore the modulation of rat frontal cortex Na+, K+ -ATPase activity induced by aspartame metabolites.

BACKGROUND: Studies have suggested that aspartame (ASP) ingestion is implicated in neurological problems. AIM: The aim of this study was to evaluate rat frontal cortex Na+, K+ -ATPase and Mg2+ -ATPase activities after incubation with ASP or each of its metabolites, phenylalanine (Phe), methanol (MeOH) and aspartic acid (asp) separately. METHOD: Suckling rat frontal cortex homogenates or pure Na+, K+ -ATPase were incubated with ASP metabolites. Na+, K+ -ATPase and Mg2+ -ATPase activities were measured spectrophotometrically. RESULTS: Incubation of frontal cortex homogenate or pure Na+, K+ -ATPase with various ASP concentrations as expected in the cerebrospinal fluid (CSF) after ASP consumption of 34, 150 or 200mg/kg, decreased the frontal cortex enzyme activity by 33%, 53% or 57%, respectively, whereas pure enzyme was remarkably stimulated. Moreover, incubation of frontal cortex homogenate with each one of the expected ASP metabolites in the CSF, except MeOH, which are related to the intake of the above mentioned doses of the sweetener, resulted in an activation of the membrane Na+, K+ -ATPase, as well as pure enzyme. Frontal cortex Mg2+-ATPase remained unaltered. Addition of l-cysteine (cys) or reduced glutathione (GSH) to ASP metabolites mixtures, corresponding to 150 or 200mg/kg doses of the sweetener, completely or partially restored to normal the modulated membrane and pure Na+, K+ -ATPase activities. CONCLUSION: CSF concentrations of the sum of ASP metabolites corresponding to the intake of common, abuse or toxic doses (34 or 150 or 200mg/kg, respectively) of the additive significantly increased rat frontal cortex Na+, K+ -ATPase and pure enzyme activities. Cys or GSH completely or partially restored to normal both enzyme activities, possibly due to amelioration of the cellular GSH reduction from the action of MeOH, a metabolite of the sweetener and/or by their scavenging effect.

The in vivo and in vitro effects of L-carnitine supplementation on the erythrocyte membrane acetylcholinesterase, Na+, K+-ATPase and Mg2+-ATPase activities in basketball players.

BACKGROUND: We investigated whether the activities of erythrocyte membrane acetylcholinesterase (AChE), Na+, K+-ATPase and Mg2+-ATPase are modulated in basketball players pre- vs. post-forced training with or without L-carnitine (L-C) supplementation. METHODS: Blood was obtained from 10 male players pre-game (group A) and post-game (group B) and after 1 month L-C supplementation (2 g/24 h orally) pre-training (group C) and post-training (group D). Lactate, pyruvate and total antioxidant status (TAS) were measured with commercial kits, catecholamines with HPLC and the enzyme activities spectrophotometrically. RESULTS: Lactate, pyruvate, AChE, Na+, K+-ATPase and catecholamines were increased (p<0.001) and TAS was decreased (p<0.001) in group B. In contrast, TAS remained unaltered and the all enzyme activities were reduced (p<0.001) in group D at the same time of study. Mg2+-ATPase activity remained unchanged. In vitro incubation of the modulated AChE and Na+, K+-ATPase with L-C (25 microM) from group B and group D resulted in a non-significant reduction of the enzymes in group B and complete restoration of their activities in group D. CONCLUSIONS: The increase of AChE and Na+, K+-ATPase activities may be due to the elevation of catecholamines in group B. Carnitine utilization by the muscles during training may result in a reduction of the enzyme activities (group D). The latter is supported by the recovery of the enzyme activities after incubation of the membranes from group D with L-C.

The effect of aspartame metabolites on the suckling rat frontal cortex acetylcholinesterase. An in vitro study.

UNLABELLED: Aspartame (ASP) consumption is suggested to be implicated with muscarinic dysfunction. The aim of this work was to evaluate the effect of ASP and its metabolites on acetylcholinesterase (AChE) activity in rat frontal cortex and pure enzyme. Rat frontal cortex homogenate or pure enzyme AChE (eel E. Electricus) were incubated with ASP and each of ASP components, phenylalanine (Phe), aspartic acid (asp), and methanol (MeOH) for 1 h at 37 degrees C. AChE was measured spectrophotometrically. The results showed that incubation of rat tissue or pure enzyme with the sum of ASP metabolites, as reported to be found in the CSF after 150 or 200 mg/kg ASP consumption, inhibited frontal cortex and pure AChE about -11% to -29% (p<0.001). Asp, Phe or MeOH concentrations related to their CSF levels after ingestion of abuse or toxic ASP doses, when separately incubated with frontal cortex or pure AChE, resulted in a significant decrease of the enzyme activities. IN CONCLUSION: ASP compounds may directly and/or indirectly act on the frontal cortex AChE. High or toxic doses of the sweetener remarkably decreased the enzyme activity. If this in vitro finding comes into human reality, it may be suggested that cholinergic symptoms are related to the consumption of the above ASP doses.

L-Cysteine and glutathione restore the reduction of rat hippocampal Na+, K+-ATPase activity induced by aspartame metabolites.

Studies have implicated aspartame (ASP) ingestion in neurological problems. The aim of this study was to evaluate hippocampal Na(+),K(+)-ATPase and Mg(2+)-ATPase activities after incubation with ASP or each of ASP metabolites, phenylalanine (Phe), methanol (MeOH) and aspartic acid (asp) separately. Suckling rat hippocampal homogenates or pure Na(+),K(+)-ATPase were incubated with ASP metabolites. Na(+),K(+)-ATPase and Mg(2+)-ATPase activities were measured spectrophotometrically. Incubation of hippocampal or pure Na(+),K(+)-ATPase with ASP concentrations (expected in the cerebrospinal fluid (CSF)) after ASP consumption of 34, 150 or 200mg/kg resulted in hippocampal enzyme activity reduction of 26%, 50% or 59%, respectively, whereas pure enzyme was remarkably stimulated. Moreover, incubation with hippocampal homogenate of each one of the corresponding in the CSF ASP metabolites related to the intake of common, high/abuse doses of the sweetener, inhibited Na(+),K(+)-ATPase, while pure enzyme was activated. Hippocampal Mg(2+)-ATPase remained unaltered. Addition of l-cysteine (cys) or reduced glutathione (GSH) in ASP mixtures, related with high/toxic doses of the sweetener, completely or partially restored the inactivated membrane Na(+),K(+)-ATPase, whereas the activated pure enzyme activity returned to normal. CSF concentrations of ASP metabolites related to common, abuse/toxic doses of the additive significantly reduced rat hippocampal Na(+),K(+)-ATPase activity, whereas pure enzyme was activated. Cys or GSH completely or partially restored both enzyme activities.

The effect of aspartame on acetylcholinesterase activity in hippocampal homogenates of suckling rats.

BACKGROUND: Neurological disturbances have been implicated with aspartame (ASP) consumption and the cholinergic system with acetylcholinesterase (AChE) seems actively involved. AIM: To evaluate the effect of ASP and its metabolites on rat hippocampal AChE activity. METHODS: Hippocampal homogenate or pure enzyme AChE (eel E. electricus) was incubated with the sum or each of ASP components, phenylalanine (Phe), aspartic acid (asp) and methanol (MeOH) for 1h at 37 degrees C. AChE activity was measured spectrophotometrically. RESULTS: Incubation of rat tissue or pure enzyme with the sum of ASP metabolites in concentrations in CSF (the concentrations were calculated according to the CSF/plasma concentration ratios) following 150 or 200mgkg(-1) of ASP consumption, resulted in significant enzyme activity reductions of 25 and 31% for hippocampal AChE and 11% (p<0.01) and 19% for pure enzyme, respectively. Aspartic acid concentrations of 0.42 or 0.56mM significantly reduced the enzyme activities by 13 and 20% for hippocampal AChE and 15 and 18% for pure enzyme, respectively. Phe concentrations of 0.042 or 0.083mM decreased the enzyme activity by 12% (p<0.01) and 20% (p<0.001) for hippocampal AChE and 15 and 18% (p<0.001) for pure enzyme, respectively. Methanol concentrations of 0.60 or 0.80mM remarkably inhibited hippocampal AChE by about 18 and 22% and pure enzyme by about 14 and 20%, respectively. CONCLUSIONS: Low concentrations of ASP components had no effect on hippocampal and pure AChE activity, whereas high or toxic concentrations remarkably decreased both enzyme activities. Muscarinic symptoms may be related to the latter concentrations of ASP metabolites.

L-cysteine supplementation prevents exercise-induced alterations in human erythrocyte membrane acetylcholinesterase and Na+,K+-ATPase activities.

BACKGROUND: L-Cysteine (L-Cys) is implicated in the reduction of free radical production. The aim of this study was to investigate whether L-Cys supplementation prevents modulation of the activities of erythrocyte membrane acetylcholinesterase (AChE), Na(+),K(+)-ATPase and Mg(2+)-ATPase induced by free radicals in basketball players during training. METHODS: Blood was obtained from 10 basketball male players before (group A) and after a game (group B) and after 1 week of L-Cys (0.5 g/24 h orally) supplementation before (group C) and after training (group D). Lactate, pyruvate and total antioxidant status (TAS) were measured using commercial kits and the enzyme activities were determined spectrophotometrically. RESULTS: Both lactate and pyruvate levels remarkably increased after exercise. In contrast, TAS levels significantly decreased in group B, increased in group C and then declined (group D), reaching those of group A. AChE activity was statistically increased post-exercise (3.98+/-0.04 Delta OD/min x mg protein) compared with pre-training (2.90+/-0.05 Delta OD/min x mg protein, p<0.01). Na(+),K(+)-ATPase activity was also higher post-exercise (1.27+/-0.05 micromol Pi/h x mg protein) than that pre-exercise (0.58+/-0.04 micromol Pi/h x mg protein, p<0.001). When the players were supplemented with L-Cys, both AChE and Na(+),K(+)-ATPase activities remained unaltered post-exercise. Mg(2+)-ATPase activities were unchanged in all groups studied. CONCLUSIONS: L-Cys supplementation may protect the enzyme activities studied against stimulation induced by free radical production during training in athletes by ameliorating their total antioxidant capacity.

Effect of CDP-choline on hippocampal acetylcholinesterase and Na+,K(+)-ATPase in adult and aged rats.

The aim of this study was to investigate the effect of different cytidine-5'-diphosphocholine (CDP-choline) concentrations (0.1-1 mM) on acetylcholinesterase (AChE), (Na+,K+)-ATPase and Mg(2+)-ATPase activities in homogenates of adult and aged rat hippocampi. Tissues were homogenised, centrifuged at 1000 x g for 10 min and in the supernatant, AChE activity and Na+,K(+)-ATPase and Mg(2+)-ATPase activities were determined according to Ellman's method and Bowler's and Tirri's method, respectively. After an 1-3 h preincubation of the homogenised tissue with CDP-choline, a maximal AChE stimulation of about 25% for both adult and aged rats (p < 0.001) and a Na+,K(+)-ATPase activation of about 50% for adult rats (p < 0.001) and about 60% for aged rats (p < 0.001) were observed, while hippocampal Mg(2+)-ATPase activity was not influenced in either adult or aged animals. It is suggested that: CDP-choline can restore hippocampal AChE and Na+,K(+)-ATPase activities in the aged rat and thus it may play a role in improving memory performance which is impaired by aging and some neuronal disturbances.